Statusline integration

Integration vim-airline

" if you want to disable auto detect, comment out those two lines
"let g:airline#extensions#disable_rtp_load = 1
"let g:airline_extensions = ['branch', 'hunks', 'coc']

let g:airline_section_error = '%{airline#util#wrap(airline#extensions#coc#get_error(),0)}'
let g:airline_section_warning = '%{airline#util#wrap(airline#extensions#coc#get_warning(),0)}'

Check out :h coc-status-airline for detail.

Integration with lightline.vim

Use configuration like:

let g:lightline = {
      \ 'colorscheme': 'wombat',
      \ 'active': {
      \   'left': [ [ 'mode', 'paste' ],
      \             [ 'cocstatus', 'readonly', 'filename', 'modified' ] ]
      \ },
      \ 'component_function': {
      \   'cocstatus': 'coc#status'
      \ },
      \ }

Use manual function

function! StatusDiagnostic() abort
  let info = get(b:, 'coc_diagnostic_info', {})
  if empty(info) | return '' | endif
  let msgs = []
  if get(info, 'error', 0)
    call add(msgs, 'E' . info['error'])
  endif
  if get(info, 'warning', 0)
    call add(msgs, 'W' . info['warning'])
  endif
  return join(msgs, ' ')
endfunction

Then add %{StatusDiagnostic()} ` to your 'statusline' option.